title: Usefulness of serum S100B as a marker for the acute phase of aquaporin-4 autoimmune syndrome.
abstract: The aquaporin-4 (AQP4) water channel antibody is used in the diagnosis of neuromyelitis optica (NMO) due to its high sensitivity and high specificity. However, some patients are reported to have neither optic neuritis nor myelitis despite being positive for the AQP4-autoantibody (AQP4-Ab). Therefore, recent reports suggest that such patients should be diagnosed as having 'AQP4-autoimmune syndrome'. In this study, we quantified the levels of glial fibrillar acidic protein (GFAP) and S100B by enzyme-linked immunosorbent assay (ELISA) in CSF and serum samples simultaneously obtained in the acute phase of ten AQP4-autoantibody (AQP4Ab)-positive and seven AQP4Ab-negative patients. Serum levels of S100B were significantly higher in the acute phase of the AQP4Ab-positive patients (2.92±1.22pg/ml) than in the AQP4Ab-negative patients (0.559±0.180pg/ml, p=0.0250), while serum levels of GFAP were not different between the two groups (AQP4Ab-positive vs. AQP4Ab-negative: 0.120±0.113ng/ml vs. 0.00609±0.00609ng/ml, p=0.193). Furthermore, the CSF and serum levels of S100B had a significant positive correlation in AQP4Ab-positive patients (n=10, r=0.673, p=0.0390). Our results raise the possibility that serum levels of S100B, but not GFAP, examined in the acute phase of the disease might be a useful biomarker for the relapse of AQP4 autoimmune syndrome.
authors.affiliation: Department of Neurology, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan. chihiro0612tsu@yahoo.co.jp
authors.forename: Chihiro
authors.initials: C
authors.lastname: Fujii
authors.forename: Takahiko
authors.initials: T
authors.lastname: Tokuda
authors.forename: Noriko
authors.initials: N
authors.lastname: Ishigami
authors.forename: Toshiki
authors.initials: T
authors.lastname: Mizuno
authors.forename: Masanori
authors.initials: M
authors.lastname: Nakagawa
mesh_terms: D000328:Adult; D000368:Aged; D051401:Aquaporin 4 / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood / Q000276:immunology; D001327:Autoimmune Diseases / Q000097:blood* / Q000134:cerebrospinal fluid / Q000276:immunology; D015415:Biomarkers / Q000097:blood / Q000134:cerebrospinal fluid; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000097:blood / Q000134:cerebrospinal fluid / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009414:Nerve Growth Factors / Q000097:blood* / Q000134:cerebrospinal fluid / Q000276:immunology; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000097:blood* / Q000134:cerebrospinal fluid / Q000276:immunology
chemical_list: D051401:Aquaporin 4; D001323:Autoantibodies; D015415:Biomarkers; D005904:Glial Fibrillary Acidic Protein; D009414:Nerve Growth Factors; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C579160:S100B protein, human